Flow machines of the previously indicated type are counted as belonging to the state of the art. The present invention departs from the state of the art, as for example the axial pumps produced and marketed by the applicant under the type description Grundfos KPL and Grundfos KWM and are counted as belonging to the state of the art. Hereby, it is the case of pumps which are typically inserted into pipes which have a diameter between 500 and 1,600 mm, with drive powers between approx. 10-1,000 kW. Such axial pumps operated in a standing manner, to which the so-called mixed flow pumps also belong, comprise an inner, essentially rotationally symmetrical housing part which receives the electrical drive motor, whose shaft is led out in a sealed manner at the lower side of the housing and is provided with a propeller as a pump impeller. This propeller is rotatably arranged within an annular channel between the inner housing part and an outer housing part, these housing parts being connected to one another via ribs and forming the delivery channel of the pump. Thereby, the essentially tubular, outer housing part is envisaged for integration into a pipe, in which the pump is arranged, and through which the fluid delivered by the pump, in particular water, is led further on the pressure side.
Such pumps are applied for delivering large quantities of water.
The inner housing part is sealed to the shaft, in order to protect the inside of the inner housing part, in which the electrical drive motor is arranged, from the penetration of delivery fluid. A chamber is provided in the region of these seals, within the inner housing part below the electric motor and the main bearing, and this chamber is envisaged for receiving a fluid buffer, for example oil, which on the one hand cools the seals and on the other hand forms an additional leakage protection.
This oil buffer, which with smaller pumps of this construction type is of a few liters, can be of 30-40 liters with large pumps. The pump is firstly to be removed from the pipe or the corresponding installation space, whereupon an opening is then to be released in the inner housing part, through which opening the oil buffer can then flow away and later be replaced by a new one, in order to change the oil buffer. The pump is brought out of its typically standing operational position, with which the longitudinal and rotation axis is arranged essentially vertically, into a horizontal position, in order to ensure the discharge of the oil through the opening. The pump is accordingly to be rotated so that the filling opening is arranged at the top, for the subsequent filling of the oil buffer. This leads to the fact that the change of the oil buffer is quite cumbersome with such a pump, since the heavy pump must be brought into a lying position and suitably handled there. The emptying and filling via the opening also takes up a considerable amount of time.